Rectifier roll support



March 27, 1962 HORNBOSTEL RECTIFIER ROLL SUPPORT 3 Sheets-Sheet 1 Filed Sept. 2, 1958 March 27, 1962 L. HORNBOSTEL 3,026,934

RECTIFIER ROLL SUPPORT Filed Sept. 2, 1958 3 Sheets-Sheet 2 fiYF/Efl/UF LLOYD HOP/14905721 bri 17 5 March 27, 1962 L. HORNBOSTEL 3,026,934

RECTIFIER ROLL SUPPORT Filed Sept. 2, 1958 3 Sheets-Sheet 3 iHlllIlIlIllll-HII ZZZVEH/UF LLOYD AURA/B05721 3,026,934 RECTIFER ROLL SUPPQRT Lloyd Hornbostel, Beloit, Wis, assignor to Beloit Iron Worlts, Beloit, Wis., a corporation of Wisconsin Filed Sept. 2, 1958, Ser. No. 753,251 11 Claims. (Cl. 162-342) This invention relates to a flow evener type of stock inlet for a paper making machine, and more particularly, to a rectifier roll assembly for such flow evener device.

The use of rectifier rolls to cause uniform stock flow is well understood. Such rectifier rolls comprise a radially perforated cylindrical tube, which usually has a plurality of disks or radial bafiies extending across the interior of the tube and axially spaced along the length thereof; but which does not have an axially aligned shaft passing through the center of the tube. Instead, the tube is equipped with heads at opposite ends thereof and the heads are provided with shafts which extend through the side walls of the head box to be received by bearings rotatably supporting the same. The stock flows transversely of the rotating roll through the perforations in the tube, and these perforations in cooperation with the radial bafiles reduce across velocities and eddy currents in the stock streams flowing therethrough, so as to obtain more or less rectilinear stock flow exiting from the rectifier roll. In order to assure such rectilinear fiow an axially aligned concentric shaft is not mounted within the tube for supporting the same for rotation.

As previously mentioned, the tube is supported for rotation by shafts which are mounted on heads at the ends of the tube. The instant invention resides in an improved method of mounting the rectifier roll for rotation. As will be appreciated, the rectifier roll has an appreciable amount of weight (so that the roll itself sags slightly in the middle) and this weight must be carried by the shafts mounted for rotation in bearings. For years only a single hearing has been employed to mount each shaft. The shaft in such prior art arrangement was, in effect, supported by the hearing at one end only and the unsupported end thereof directly connected to the head was urged downwardly by the weight of the rectifier roll. This developed a moment in the shaft which must be resisted by an opposite moment in the head per se. Of course, this tended to cause failures in the heads, unless the heads were made of substantial size and thickness or were reinforced (in each case by structure extending into the roll), and it also tended to cause other operating failures or deficiencies, for example, in the packing which forms a sealing between the shaft and the side walls of the stock flow conduit. At first, the causes for such failures were not fully appreciated, but they are now believed to be caused primarily by the development of such moments. The instant invention provides a bearing mounting which overcomes the development of the moment in the shaft. The sagging of the roll shell tends to maintain the heads in planes at an angle to the vertical so moment is imparted to the heads. This moment is resisted by the shafts; but the instant heads are themselves resilient, or preferably contain a resilient element for continuously absorbing such moment during rotation of the roll shell.

It is, therefore, an important object of the instant in vention to provide an improved rectifier roll assembly, and a stock flow evener comprising the same.

It is another object of the instant invention to provide an improved rectifier roll assembly wherein the rectifier roll shafts are supported in each case by a plurality of axially spaced bearings, and resilient means are interposed between the shafts and the roll.

Other and further objects, features and advantages will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings:

FIGURE 1 is a sectional elevational view, with some parts shown diagrammatically, of a flow evener for a paper machine embodying the instant invention;

FIGURE 2 is a sectional elevational view taken substantially along the line IllI of FIGURE 1 showing in detail the bearing mounting for the rectifier roll shaft;

FIGURE 3 is a view comparable to FIGURE 1 showing another arrangement for a flow evener; and

FIGURES 4, 5 and 6 are views comparable to FIGURE 2 showing different head structures.

.As shown on the drawings:

In FIGURE 1, the reference numeral 10 indicates gen- 7 erally an inlet box for a Fourdrinier type paper making machine, the box 10 receiving the stock from an upwardly directed inlet conduit 11 for subsequent introduction onto the forming wire 12 wrapped about a breast roll 13 in a conventional Fourdrinier type paper making machine. The stock flows through the conduit or box 19 from the inlet conduit 11 to and through a stock outlet in the form of a slice 14 and onto the forming wire 12 where the web W is formed.

The inner box it} may be a closed box provided with air pressure supply means (not shown) for accelerating the flow of stock to the slice 14, or the inlet box 19 may be as shown an open topped inlet box which is defined generally by a bottom wall 15 terminating in a forward. apron portion 15a, a pair of side walls 16 (only oneof which is shown), a rear wall (not shown) and a front wall. 17 overlying the breast roll 13. The stock flowing in the box lll is maintained at the level L by suita-bleflow con-- trol and level control means (not shown). The stock thus flows at the level L from the stock inlet 11 to the stock outlet or slice 14 between the side walls 16, 16. x 3

A plurality (which may be more than the two here shown) of rectifier rolls 18 and 19, in the form of verti cally stacked or superimposed rolls 18 and 19, are positioned between the inlet 11 and the outlet 14 as'here shown near the inlet 11, so as to extend between the side walls 16, 16 and to cooperate with each other in close running relationship to substantially prevent flow of stock therebetween except through one of the rolls 18 or 1 9. The stack of rolls 18 and 19 thus extends from the floor 15 to approximately the stock level L, and there is minimum clearance between the roll 18 and the floor 15 and the roll 18 and the roll 19. Suitable journaling means indicated at 20 and 21 are provided for rotation of the rolls in the positions indicated. Such journaling means are mounted in the sidewalls 16, 16 and their general nature and function was well understood in the art. Particularly, because of the close running between the rolls 18 and 19 and between the roll. 18 and the floor 15 such journaling means 26' and 21 are required to maintain the position of the rolls 18 and 19 precisely during operation. Generally, a positive drive means (not shown) is employed to effect the desired rate and direction of rotation of the rolls 13 and 19.

It will also be seen from FIGURE 1 that another plurality (again a pair is shown, but more may be used) of rectifier rolls 22 and 23 are positioned in superimposed bridging relationship with respect to the slice 14, so as to receive all stock flowing through the box 10 and out the slice 14. The rolls 22 and 23 are positioned in their bridging relationship as shown so that they will be spaced a short distance from the slice 14 so as to permit a reasonable amount of additional smoothing out of the flow of stock after it has departed from the rolls 22 and 23 and before it reaches the slice 14. The rolls 22 and 23 are also suitably journaled at 24 and 25 in the same manner that the rolls 18 and 19 are mounted for rotation.

Again, the shafts 24 and 25 must maintain a precise position for the rolls 22 and 23 because of their close running relationship with respect to each other and the walls and 17.

Referring now to FIGURE 2 which shows the mounting for journal means 25 for the roll 23, it will be appreciated that the mountings for each of the other journal means 21, and 24 are the same as those described in FIGURE 2. In FIGURE 2, the rectifier roll 23 has a cylindrical tube 26 having perforations 27 (only a few of which are shown) throughout the entire periphery thereof. The perforated cylindrical tube 26 has a head 28 mounted at each end thereof. The head 28 comprises a plurality of thin resilient disk-shaped members 28a, 28b, 28c clamped at their outer periphery against an annular shoulder 26a on the shell 26 by a ring 26b seated in a groove 260. The thin members 28a, 28b, 28c absorb the moment changes exerted by the rotating (sagging) shell 26 on the shaft and vice versa; these members resist forces applied to the planes thereof but are resilient (compared to the structures of the shafts 25 and shell 26) so as to allow slight deflection thereof during rotation. Since it is apparent that the elements of the head 28 lie substantially in the same plane (and do not extend inwardly into the shell or have support members which do extend inwardly into the shell), the head 23 may be described as uniplanar. The shaft 25 is mounted concentrically on the head 28 and extends through the side wall 16. A plurality of axially spaced bearings 29 and 30 rotatably receive the shaft 25 outside the stock conduit side wall 16.

Referring now to the details of the mounting for the shaft 25, it will be seen that the side wall 16 (shown only partially) is provided with an annular packing housing 31a securely mounted in the aperture 16a receiving the shaft 25 in the wall 16. The packing housing 31a has an annular packing and sealing element 31 retained therein by apacking ring 32 in the usual manner; and a lubrication fitting F of standard design is mounted in the housing 31a to provide lubrication for the packing element 31. A collar 34 is clamped to the head 28 by a collar 35 and bolts 35a, for rotation with the head 28. The collar 34 is keyed to and retains the shaft 25 in firm assembly with the head 28 and the packing element 31 is urged against the outer periphery of the collar 34 to form a liquid seal therewith to substantially prevent flow of water from the stock conduit 10 out through the wall 16. An annular housing member 36 is carried by the wall 16 and secured thereto by suitable means (not shown) so as to extend outwardly therefrom and to mount concentrically a generally cylindrical bearing housing 37 secured to the annular member 36 by bolts 38. The outer extremity of the bearing housing 37 is closed by a cap 39 secured by bolts 40. As will be appreciated, the cap 39 is provided for the so-called front side of the machine, and on the back side of the machine an annular sealing member is provided which permits the journal to extend therethrough and make connection with suitable drive means (not shown). An annular oil seal 41 is secured by bolts 42 to the inside end of the bearing housing 37 to seal off the bearing housing 37 against the rotary shaft 25. The bearing housing 37, as thus shown, is sealed off so that the desired oil level may be maintained therein by suitable lubricating means (not shown). At the inside end of the bearing housing 39 a bearing 29 is mounted in the form of an outside race 29a and inside race 2% and rollers 29c mounted therebetween in the customary manner. In like manner, near the outer end of the bearing housing 37 there is mounted a bearing 30 in the form of an outside race 33a, inside race 30b and rollers 30c therebetween. A clamp ring 43 secures the inner race 30b in position. The bearings 29 and 30 are axially spaced on the shaft 25 (by at least about one diameter of the shaft 25).

The axial spacing of the bearings 29 and 30 substantially prevents downward deflection of the shaft 25 which must be resisted by the head 28. Any deflection which might develop about a single hearing, at 29, is counteracted by the second axially spaced bearing 30, rather than being resisted by the head 28. This way there is no downward deflection of the inside end 25a of the shaft 25 by the weight of the roll 23. The deflection of the head resulting from sagging of the middle of the shell 26 is absorbed by the flexible head elements 28a, 23b, 28c, which still carry the shell load on the shaft. The head 23 may thus be made of thin lightweight structural material adapted only to resist a radial force and not to resist a moment. By using a thin disk-shaped head 28 in the instant arrangement, better stock flow past the head 28 is obtained and no supports are necessary within the tube 26 which would interfere with the uniform stock flow through the tube. Also, the radial forces applied to the resilient head 28 do not have as much of a tendency to cause failures therein as the moment heretofore applied to rigid head elements.

Referring now to FIGURE 4, it will be seen that a different type of connection between a shaft 125 and a rectifier roll head 128 is shown. As will be noted, most of the elements shown in FIGURE 4 are identical to those shown in FIGURE 2 and such elements have the same reference numeral in the series. For the purpose of simplification the functions of most of such elements will not be repeated herein. As will be seen from FIG- URE 4, a collar 134 is keyed to and retained on the shaft in firm assembly and a packing element 131 is urged against the outer periphery of the collar 134 to form a liquid seal therewith to substantially prevent the flow of water from the stock conduit 100 out through the wall 116. The rectifier roll head 128 has a central aperture therein 128a which retains a resilient annular member 150. The annular member is preferably made of hardened rubber or other suitable resilient material which is capable of resisting the radial load applied thereto by the weight of the rectifier roll R carried by the head 128, but the annular resilient member 150 is sufficiently resilient to prevent the shaft 125 from imposing any moment or bending load on the head 128. The resilient ring 150 snugly receives the shaft end 125a and the resilient ring 150 is connected in firm assembly to the shaft end 125a and the head 128 by suitable means such as an adhesive or by mechanical means (not shown) so that relative axial movement between the elements is prevented. As will be noted the shaft 125 extends from substantially flush with the inside surface of the head 128 outwardly; and the head 128 is positioned in close running relation to the wall 116. In this way the perforate cylinder 126 forming the body of the rectifier roll R presents substantially the sole restriction to stock flow passing through the region occupied by the cylinder 126. The head 128 and any baflles such as the bafile 151 here shown may also be considered as restrictions to stock fiow, although their function in this respect is more to align stock flow rather than restrict the same. There are no portions of a shaft extending into the shell 126 or past the head 128, nor are there any braces extending along the inside of the head 128 to make firm assembly with the shaft 125; and it will be appreciated that such shaft hubs and braces, used in the prior art, formed a definite restriction to stock flow and interrupted the straight line flow of the stock along the walls of the inlet. The instant arrangement avoids this disturbance in the stock flow. The flexible connection 150 between the shaft 125 and the head 128 completely eliminates the application of any moment or bending forces to the head 128 and makes possible the use of a very thin metal sheet for the head 128.

Referring now to FIGURE 3, it will be seen that there is shown a flow evener or stock inlet 1% having an inlet conduit 111, a bottom wall 115, a top wall 115ba front wall 117, a rear wall 117a, and side walls, only one of which 117b is shown. The front wall 117 and the bottom wall 115 cooperate to define a slice outlet 114 from which stock flows onto a forming wire 112 wrapped about a breast roll 113 to form a web W. In the particular arrangement of the inlet lill), only a single rectifier roll R (of FIGURE 4) is mounted in the slice outlet 114 and has substantially the height and width of the slice outlet 114, extending the entire width between the side walls 117b, 117b.

The inlet 100 is a closed box provided with a source of air under pressure such as a pump 152 (shown diagrammatically) for exerting air pressure against the top level L of the stock in the box 100. A level control device, such as a blow hole 153 is provided. in the box ltltl for maintaining the level L at substantially the top of the rectifier roll R (or just sufficient to submerge the rectifier roll R). In this way the roll R provides the sole restriction to stock flow through the inlet box 130. In this respect, it will be noted that the perforate shell 126 of the rectifier roll R actually presents the sole restriction to stock flow through the inlet. As previously mentioned, any bafiies 151 in the perforate shell 126 and the heads 128 therefor also may be considered to present a slight restriction to stock flow, although their function is primarily that of aligning stock fiow. In any event, nothing else in the inlet box 100 (or in this case nothing else in the slice outlet 114) presents any restriction to stock flow therethrough with the exception of the perforate shell 126, baffles 151, and the heads 128. There are no other supporting elements within the rectifier roll R; there are no braces supporting the heads 128; and there are no shaft hubs extending into the cylindrical shell or tube 126.

It will also be appreciated that a plurality of coplanar rectifier rolls may be included in the box 104), all having the same structure as. the roll R and extending from the bottom to the stock level L.

Referring now to FIGURE 5, it will be seen that a different type of connection between a shaft 225 and a rectifier roll head 228 is shown. It will be noted that most of the elements shown in FIGURE 5 are identical to those shown in FIGURES 2 and 4 and such elements have the same reference numeral in the 200 series. For the purpose of simplification, the functions of most of such elements Will not be repeated herein. As will be seen, axially spaced bearings 229 and 239 (shown diagrammatically) are mounted within a housing 237 that is provided with a cap 239 and an oil seal 241. The housing 237 is here shown mounted on a suitable foundation 269. The housing 237 receives the shaft 225 and cantileverly supports the same as it extends just through the head box wall 216. The shell 226 is again provided with perforations 227 and is mounted by suitable means (not shown) on a head 228. The head is a generally flat disk-shaped member lying in close running relation to the wall 216. A collar 234 extends through the wall 216 and is connected to the central portion of the head 228 by bolts 235a. The collar 234 rotates with the head 228 and is sealed by a packing gland 231a, 231, 232. A rubber sleeve 245 is secured to the inner extremity of the shaft 225 just as it passes through the head box wall 216. The resilient solid elastomer sleeve 245 is preferably made of rubber and is vulcanized to the shaft 225 and the collar 234 (but not to the head 228), so that during disassembly the bolts 235a may be withdrawn and the shaft 225, rubber sleeve 245 and collar 234 may be moved axially outwardly and the shell 226 (with head 228 attached) may then be removed directly out of the top of the head box without further work. Here, the resilient sleeve 245 carries out a function comparable to that of the resilient sleeve 128 of FIGURE 4.

Referring now to FIGURE 6, it will be seen that elements similar to those disclosed in FIGURES 2, 4 and 6 5 will be given the same reference numeral in the 300 series. A shaft 325 mounted on axially spaced bearings 329 and 335 (shown diagrammatically) extends inward ly to just inside the head box wall 316. A packing gland 331a, 331 and 332 effectively seals the shaft 325 so as to prevent flow of stock from the head box outwardly. The shell 326 has a head 328 suitably connected thereto (by means not shown) and the head is a generally fiat disk-shaped member that rotates in close running relation to the wall 316 in assembly. For convenience, the arrangement of FIGURE 6 is shown in an exploded view. The head 323 is provided with a socket 356 that has a plurality of grooves of short axial dimension cut in the inner periphery thereof at 351. Also, near the outer edge of the socket 350 there is a single annular groove cut in the periphery thereof at 352 which is adapted to receive an O-ring seal 353 (shown in the exploded view). The shaft 325 is provided with a head 354 at its outer extremity mounting a plurality of mating ridges 355 for the grooves in the inner periphery 351 of the socket 351 The ridges 355 and the grooves at 351 are a loose fit, so that rocking or tilting motion resulting from the sagging of the shell 326 will be absorbed at the groove end socket assembly 351, 355, but actual driving or corotation of the head 328 and the shaft 325 is efiected. The ridges 355 may be crowned if they are of substantial axial dimension, but if they are of short axial dimension as here shown, relative tilting between the shaft 325 and the head 328 is accommodated by this connection, which is the mechanical counterpart to the previously described flexible and resilient connections. The shafthead 354 is also provided with a groove 356 for seating the O-ring seal 353 when in assembly. The O-ring seal 353 is intended to prevent the flow of stock into the socket 350. In order to assure that stock does not flow into the socket 350' and clog up the flexible connection between the grooves 351 and the ridges 355, a suitable source of water under pressure (indicated diagrammatically at S) is connected to an axial bore 357 within the journal 325. The axial bore feeds water under pressure into the base 358 of the socket 350, back between the ridges 355 in the grooved portion 351 and against the O-ring seal 353. A slight seepage past the O-ring seal assures that no stock will flow inwardly.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

I claim as my invention:

1. In a flow evener for a paper machine having members defining a stock flow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll having a perforated cylindrical tube, heads at opposite ends of the tube, resilient elements on the heads which are permitted to flex during rotation of the roll and shafts mounted on the resilient elements and extending through the side walls; and a plurality of axially spaced bearings rotatably receiving each shaft outside the stock conduit.

2. In a flow evener for a paper machine having members defining a stock flow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll having a perforated cylindrical tube, heads at opposite ends of the tube, resilient mounting means on the heads which are permitted to flex during rotation of the roll and shafts mounted on said mounting means and extending through the side walls; and a pair of closely spaced bearings mounted outside each side wall rotatably receiving each shaft.

3. In a flow evener for a paper machine having members defining a stock fiow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises opposed shafts extending from outside the side walls to just barely inside the same, a plurality of axially spaced bearings rotatably receiving each shaft outside of the side walls, a rectifier roll within the stock fiow conduit having a perforated cylindrical tube, heads at opposite ends of said tube in close running relation to said side walls, and resilient sleeves at the inner extremity of each of said shafts, said resilient sleeves being permitted to flex during rotation of the roll and resiliently mounting said heads so as to support the full weight of the rectifier roll and said heads.

4. In a flow evener for a paper machine having mem bers defining a stock fiow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll in the conduit having a perforate cylindrical shell having opposed open ends, shafts extending through the side walls and resilient elements mounting the shell ends on the shafts thereby affording limited tilting of the roll axis with respect to the shafts during rotation of the roll and substantially preventing the shaft from imposing any moment on the shell ends; and a plurality of axially spaced bearings rotatably receiving each shaft outside the stock conduit.

5. In a flow evener for a paper machine having members defining a stock flow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll in the conduit having a perforate cylindrical shell having opposed open ends, shafts extending through the side walls and resilient elements mounting the shell ends on the shafts thereby affording limited tilting of the roll axis with respect to the shafts during rotation of the roll and substantially preventing the shaft from imposing any moment on the shell ends; and a pair of closely spaced bearings mounted outside each side wall rotatably receiving each shaft.

6-. in a flow evener for a paper machine having members defining a stock fiow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll in the conduit having a perforate cylindrical shell, substantially uniplanar heads mounted at each end of said shell in close running relation to the side walls, shafts mounting the heads and extending from the heads outwardly through the side walls, means interposed between each shaft and the head mounted thereon forming a connection therebetween affording limited tilting of the roll axis with respect to the shafts to prevent the shafts from imposing any moment of the heads during rotation of the roll; and a plurality of axially spaced bearings rotatably receiving each shaft outside the stock conduit.

7. In a flow evener for a paper machine having members defining a stock flow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll in the conduit having a perforate cylindrical shell, substantially uniplanar heads mounted at each end of said shell in close running relation to the side walls, shafts mounting the heads and extending from the heads outwardly through the side walls, solid elastomer sleeves interposed between each shaft and the head mounted thereon forming a connection therebetween affording limited tilting of the roll axis with respect to the shafts to prevent the shafts from imposing any moment on the heads during rotation of the roll; and a plurality of axially spaced bearings rotatably receiving each shaft outside the stock conduit.

8. In a flow evener for a paper machine having members defining a stock flow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll in the conduit having a perforate cylindrical shell, substantially uniplanar heads mounted at each end of said shell in close running relation to the side walls, sockets in said heads, shafts extending through the side walls and terminating in said sockets, means affording driving engagement between each shaft and the head mounted thereon forming a connection therebetween affording limited tilting of the roll axis with respect to the shafts to prevent the shafts from imposing any moment on the heads during rotation of the roll.

9. In a flow evener for a paper machine having members defining a stock flow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises arectifier roll in the conduit having a perforate cylindrical shell, substantially uniplanar heads mounted at each end of said shell in close running relation to the side walls, sockets in said heads, shafts extending through the side walls and terminating in said sockets, solid elastomer sleeves in said sockets affording driving engagement between each shaft and the head mounted thereon forming a connection therebetween affording limited tilting of the roll axis with respect to the shafts to prevent the shafts from imposing any moment on the heads during rotation of the roll.

10. In a fiow evener for a paper machine having members defining a stock fiow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll in the conduit having a perforate cylindrical shell, substantially uniplanar heads mounted at each end of said shell in close running relation to the side walls, sockets in said heads, shafts extending through the side walls and terminating in said sockets, loosely engaged ridges and grooves in the sockets and on the shafts affording driving engagement between each shaft and the head mounted thereon forming a connection therebetween affording limited tilting of the roll axis with respect to the shafts to prevent the shafts from imposing any moment on the heads.

11. in a flow evener for a paper machine having members defining a stock flow conduit from a stock inlet to a stock outlet between side walls, the improvement which comprises a rectifier roll having a perforated cylindrical tube, heads at opposite ends of the tube, socket elements on the heads having an axial groove in the inner wall thereof, shaft members having a corresponding axial tongue thereon, loosely inserted into said socket members, said shafts extending through the side walls, means fiowing liquid through said shafts into said socket, and a plurality of axially spaced bearings rotatably receiving each shaft outside the stock conduit.

References Cited in the file of this patent UNITED STATES PATENTS 2,l74,223 Frauenthal et a1 Sept. 26, 1939 2,390,977 Williams Dec. 11, 1945 2,440,727 Rosrnait May 4, 1948 2,444,904 Worley July 6, 1948 2,713,970 Kueser July 26, 1955 2,722,164 Duncan Nov. 1, 1955 2,749,815 Stewart June 12, 1956 2,870,616 Benson Jan. 27, 1959 

